System and method for capturing and decontaminating photoplethysmopgraphy (PPG) signals in a vehicle

ABSTRACT

A system and method for processing photoplethysmography (PPG) signals in a vehicle. The system and method include receiving a PPG waveform signal from an optical sensor. The system and method also include processing a PPG measurement signal based on the PPG waveform signal. The system and method additionally include receiving a noise waveform signal from at least one of: a seat assembly sensor, a vehicle sensor, and a vehicle system. Additionally, the system and method include processing a motion artifacts measurement signal based on the noise waveform signal. The system and method further include processing a refined PPG signal to suppress the motion artifacts measurement signal from the PPG measurement signal.

The application is a continuation-in-part of, and claims priority toU.S. application Ser. No. 13/858,038, filed on Apr. 6, 2013, the entireapplication of which is incorporated herein by reference.

BACKGROUND

Photoplethysmography (PPG) provides a non invasive optical technique todetect changes in blood volume and blood composition in a biologicalbeing. However, PPG readings are susceptible to contamination by noisein the form of motion artifacts that can impact the usefulness of PPGdata for biometric interpretation. Specifically, within a vehicleenvironment, motion artifacts can be enhanced based on noise, roadvibration, individual movement, vehicle movement, inertial movement,among others. Motion artifacts become an exceptional property ofcaptured PPG signals that pollute PPG readings and provide a skewedbiometric interpretation.

BRIEF DESCRIPTION

According to one aspect, a computer implemented method for processingphotoplethysmography (PPG) signals in a vehicle includes receiving a PPGwaveform signal from an optical sensor. The method also includesprocessing a PPG measurement signal based on the PPG waveform signal.The method additionally includes receiving a noise waveform signal fromat least one of: a seat assembly sensor, a vehicle sensor, and a vehiclesystem. Additionally, the method includes processing a motion artifactsmeasurement signal based on the noise waveform signal. The methodfurther includes processing a refined PPG signal to suppress the motionartifacts measurement signal from the PPG measurement signal.

According to a further aspect, a system for processingphotoplethysmography (PPG) signals in a vehicle includes a computingdevice that includes a processor. The system also includes a PPGdeterminant module that is included as a module of the computing devicethat receives a PPG waveform signal from an optical sensor and processesa PPG measurement signal based on the PPG waveform signal. Additionally,the system includes a motion artifacts determinant module that isincluded as a module of the computing device that receives a noisewaveform signal from at least one of: a seat assembly sensor, a vehiclesensor, and a vehicle system and processes a motion artifactsmeasurement signal based on the noise waveform signal. The systemfurther includes a PPG signal filtering module that is included as amodule of the computing device that processes a refined PPG signal tosuppress the motion artifacts measurement signal from the PPGmeasurement signal.

According to still another aspect, a computer readable medium a computerreadable medium including instructions that when executed by a processorexecutes a method for processing photoplethysmography (PPG) signals in avehicle includes receiving a PPG waveform signal from an optical sensor.The method also includes processing a processing a PPG measurementsignal based on the PPG waveform signal. The method additionallyincludes receiving a noise waveform signal from at least one of: a seatassembly sensor, a vehicle sensor, and a vehicle system. Additionally,the method includes processing a motion artifacts measurement signalbased on the noise waveform signal. The method further includesprocessing a refined PPG signal to suppress the motion artifactsmeasurement signal from the PPG measurement signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an operating environment for implementingsystems and methods for capturing and decontaminating PPG signals in avehicle according to an exemplary embodiment;

FIG. 2A is a schematic view of an optical sensor according to anexemplary embodiment;

FIG. 2B is a schematic representation of an exemplary PPG measurementsignal, a noise measurement signal, and a refined PPG signal accordingto an exemplary embodiment;

FIG. 3 is a process flow diagram of an exemplary method for processing aPPG measurement signal from one or more PPG waveform signals from theoperating environment of FIG. 1 according to an exemplary embodiment;and

FIG. 4 is a process flow diagram of a method for processing PPG signalsin a vehicle from the operating environment of FIG. 1 according to anexemplary embodiment.

DETAILED DESCRIPTION

The following includes definitions of selected terms employed herein.The definitions include various examples and/or forms of components thatfall within the scope of a term and that can be used for implementation.The examples are not intended to be limiting.

A “bus”, as used herein, refers to an interconnected architecture thatis operably connected to other computer components inside a computer orbetween computers. The bus can transfer data between the computercomponents. The bus can be a memory bus, a memory controller, aperipheral bus, an external bus, a crossbar switch, and/or a local bus,among others. The bus can also be a vehicle bus that interconnectscomponents inside a vehicle using protocols such as Media OrientedSystems Transport (MOST), Controller Area network (CAN), LocalInterconnect Network (LIN), among others.

“Computer communication”, as used herein, refers to a communicationbetween two or more computing devices (e.g., computer, personal digitalassistant, cellular telephone, network device) and can be, for example,a network transfer, a file transfer, an applet transfer, an email, ahypertext transfer protocol (HTTP) transfer, and so on. A computercommunication can occur across, for example, a wireless system (e.g.,IEEE 802.11), an Ethernet system (e.g., IEEE 802.3), a token ring system(e.g., IEEE 802.5), a local area network (LAN), a wide area network(WAN), a point-to-point system, a circuit switching system, a packetswitching system, among others.

A “disk”, as used herein can be, for example, a magnetic disk drive, asolid state disk drive, a floppy disk drive, a tape drive, a Zip drive,a flash memory card, and/or a memory stick. Furthermore, the disk can bea CD-ROM (compact disk ROM), a CD recordable drive (CD-R drive), a CDrewritable drive (CD-RW drive), and/or a digital video ROM drive (DVDROM). The disk can store an operating system that controls or allocatesresources of a computing device.

A “database”, as used herein can refer to table, a set of tables, a setof data stores and/or methods for accessing and/or manipulating thosedata stores. Some databases can be incorporated with a disk as definedabove.

A “memory”, as used herein can include volatile memory and/ornon-volatile memory. Non-volatile memory can include, for example, ROM(read only memory), PROM (programmable read only memory), EPROM(erasable PROM), and EEPROM (electrically erasable PROM). Volatilememory can include, for example, RAM (random access memory), synchronousRAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double datarate SDRAM (DDR SDRAM), and direct RAM bus RAM (DRRAM). The memory canstore an operating system that controls or allocates resources of acomputing device.

A “module”, as used herein, includes, but is not limited to,non-transitory computer readable medium that stores instructions,instructions in execution on a machine, hardware, firmware, software inexecution on a machine, and/or combinations of each to perform afunction(s) or an action(s), and/or to cause a function or action fromanother module, method, and/or system. A module may also include logic,a software controlled microprocessor, a discrete logic circuit, ananalog circuit, a digital circuit, a programmed logic device, a memorydevice containing executing instructions, logic gates, a combination ofgates, and/or other circuit components. Multiple modules may be combinedinto one module and single modules may be distributed among multiplemodules.

An “operable connection”, or a connection by which entities are“operably connected”, is one in which signals, physical communications,and/or logical communications can be sent and/or received. An operableconnection can include a wireless interface, a physical interface, adata interface and/or an electrical interface.

A “processor”, as used herein, processes signals and performs generalcomputing and arithmetic functions. Signals processed by the processorcan include digital signals, data signals, computer instructions,processor instructions, messages, a bit, a bit stream, or other meansthat can be received, transmitted and/or detected. Generally, theprocessor can be a variety of various processors including multiplesingle and multicore processors and co-processors and other multiplesingle and multicore processor and co-processor architectures. Theprocessor can include various modules to execute various functions.

A “portable device”, as used herein, is a computing device typicallyhaving a display screen with user input (e.g., touch, keyboard) and aprocessor for computing. Portable devices include, but are not limitedto, handheld devices, mobile devices, smart phones, laptops, tablets ande-readers. In some embodiments, a “portable device” could refer to aremote device that includes a processor for computing and/or acommunication interface for receiving and transmitting data remotely.

A “vehicle”, as used herein, refers to any moving vehicle that iscapable of carrying one or more human occupants and is powered by anyform of energy. The term “vehicle” includes, but is not limited to:cars, trucks, vans, minivans, SUVs, motorcycles, scooters, boats,go-karts, amusement ride cars, rail transport, personal watercraft, andaircraft. In some cases, a motor vehicle includes one or more engines.Further, the term “vehicle” can refer to an electric vehicle (EV) thatis capable of carrying one or more human occupants and is poweredentirely or partially by one or more electric motors powered by anelectric battery. The EV can include battery electric vehicles (BEV) andplug-in hybrid electric vehicles (PHEV). The term “vehicle” can alsorefer to an autonomous vehicle and/or self-driving vehicle powered byany form of energy. The autonomous vehicle may or may not carry one ormore human occupants. Further, the term “vehicle” can include vehiclesthat are automated or non-automated with pre-determined paths orfree-moving vehicles.

A “vehicle system”, as used herein can include, but is not limited to,any automatic or manual systems that can be used to enhance the vehicle,driving and/or safety. A “vehicle system”, as used herein can include,but is not limited to, any automatic or manual systems that can be usedto enhance the vehicle, driving and/or safety. Exemplary vehicle systemsinclude, but are not limited to: an electronic stability control system,an anti-lock brake system, a brake assist system, an automatic brakeprefill system, a low speed follow system, a cruise control system, acollision warning system, a collision mitigation braking system, an autocruise control system, a lane departure warning system, a blind spotindicator system, a lane keep assist system, a navigation system, atransmission system, brake pedal systems, an electronic power steeringsystem, visual devices (e.g., camera systems, proximity sensor systems),a climate control system, an electronic pretensioning system, amonitoring system, a passenger detection system, a vehicle suspensionsystem, a vehicle seat configuration system, a vehicle cabin lightingsystem, an audio system, a sensory system, among others.

A “wearable computing device”, as used herein can include, but is notlimited to, a computing device component (e.g., a processor) withcircuitry that can be worn by and/or in possession of a user. In otherwords, a wearable computing device is a computer that is subsumed intothe personal space of a user. Wearable computing devices can include adisplay and can include various sensors for sensing and determiningvarious parameters associated with a user. For example, location,motion, and biosignal (physiological) parameters, among others. Somewearable computing devices have user input and output functionality.Exemplary wearable computing devices can include, but are not limitedto, watches, glasses, clothing, gloves, hats, shirts, jewelry, rings,earrings necklaces, armbands, shoes, earbuds, headphones and personalwellness devices.

I. System Overview

Referring now to the drawings, wherein the showings are for purposes ofillustrating one or more exemplary embodiments and not for purposes oflimiting the same, FIG. 1 illustrates a system 100 for implementingsystems and methods for capturing and decontaminatingphotoplethysmography (PPG) signals in a vehicle according to anexemplary embodiment. The system 100 illustrated in FIG. 1 can beimplemented within a vehicle 102. It is to be appreciated that thecomponents of the system 100, as well as the components of other systemsand architectures discussed herein, can be combined, omitted ororganized into different architectures for various embodiments. It isalso to be appreciated, that other components not shown in FIG. 1,(e.g., a display device, communication units/gateways, communicationnetworks, and buses) or several instances of the components shown inFIG. 1 can also be included.

The system 100 can be implemented alone or in combination with acomputing device 104 (e.g., controller, a head unit, etc.). Thecomputing device 104 includes a processor 106, a memory 108, and a disk110 which are operably connected for computer communication via a bus(not shown) and/or other wired and wireless technologies.

The computing device 104 can execute software serving to monitor andsupervise various parameters of the engine (not shown) of the vehicle102, as well as other components or systems of the vehicle 102. Forexample, the computing device 104 is capable of receiving signals fromcomponents of the vehicle 102 including sensors and devices. Signalsoutput from sensors and devices can be sent to the computing device 104and can be stored on the memory 108 and/or the disk 110. Further, thecomputing device 104 can facilitate information transfer betweencomponents of the vehicle 102 and/or control of the components of thevehicle 102. Both real-time and electronically stored signals can beprocessed by the processor 106 in accordance with software stored on thememory 108 and/or the disk 110.

In some embodiments, the computing device 104 can process signal outputby sensors and devices into data formats that include values and levels.Such values and levels can include, but are not limited to, a numericalor other kind of value or level such as a percentage, a non-numericalvalue, a discrete state, a discrete value, a continuous value, amongothers. For example, in some cases, the value or level of X can beprovided as a percentage between 0% and 100%. In other cases, the valueor level of X can provided as a value in the range between 1 and 10. Instill other cases, the value or level of X may not be a numerical value,but could be associated with a determined state, such a driving state.

In an exemplary embodiment, the computing device 104 also includes a PPGdeterminant module 112, a motion artifact determinant module 114, and aPPG signal filtering module 116. As will be described in more detailbelow, the PPG determinant module 112 communicates with one morecomponents of the vehicle 102 in order to process a PPG measurementsignal (illustrated in FIG. 2B) that is associated with a driver 118 ofthe vehicle 102. The motion artifact determinant module 114 communicateswith one or more sensors disposed at different locations of the vehicle102 to determine a motion artifacts waveform that represents motionartifacts that are caused in part by the driver 118 and/or the vehicle102 in the form of a motion artifacts measurement signal (illustrated inFIG. 2B). Additionally, the PPG signal filtering module 116 cancommunicate with the PPG determinant module 112 and the motion artifactdeterminant module 114 to receive the PPG measurement signal and themotion artifacts measurement signal in order to process a refined PPGsignal (illustrated in FIG. 2B). As described in more detail below, thePPG signal filtering module 116 can process the refined PPG signal thatis decontaminated from motion artifacts. The computing device 104 canutilize the refined PPG signal to determine biometric data and/or adriver state that is associated with the driver 118.

In the illustrated embodiment of FIG. 1, the system 100 also includes asensor assembly 120 that is mechanically coupled to a vehicle seat 122(e.g., driver's side vehicle seat). It is to be appreciated that thesystem and method discussed herein can be implemented with any number ofsensor assemblies 120. Although, some embodiments discussed herein referto the sensor assembly 120, it will be appreciated that a plurality ofsensor assemblies 120 can be mechanically coupled to the vehicle seat122.

The sensor assembly 120 can include one or more sensor assembly sensors(not all individually shown) that can include contact sensors and/or noncontact sensors. The plurality of sensor assembly sensors can includeelectric current/potential (e.g., proximity sensors, inductive,capacitive), ultrasonic (e.g., piezoelectric, electrostatic), vibration,optical, vision, photoelectric or oxygen sensors, among others. It isappreciated that the one or more sensor assembly sensors are operable tosense a measurement of data associated with the driver 118, the vehicle102, the vehicle environment, one or more vehicle systems 124, and/oroccupants of the vehicle 102, and can output one or more data signalsindicating one or more measurements of data to the computing device 104.The computing device 104 can convert the data signals into other dataformats in order to generate other data metrics and parameters such asvalues and levels, as described above.

In an exemplary embodiment, one or more specific sensor assembly sensorscan include an optical sensor (illustrated in FIG. 2A) for sensing PPGsignals and additional signals to determine the driver's physiologicalstate and/or motion artifacts associated with the driver 118 and/orvehicle 102, as described in more detail below. The sensor assemblysensors can additionally include, but are not limited to, a pressuresensor, an accelerometer, and physiological sensors. In someembodiments, the physiological sensors can include, but are not limitedto, electric current/potential sensors, proximity sensors, opticalsensors, visual sensors, sonic sensors, and additional photoelectricsensors using optics and light (e.g., infrared). The sensor assemblysensors can provide various types of physiological data that can beevaluated by the computing device 104 to determine the physiologicalstate of the driver 118. Various types of physiological data that can bereceived from the sensor assembly sensors include, but are not limitedto, heart information, such as, heart rate, blood pressure, blood flow,oxygen content, blood alcohol content (BAC), brain information, such as,functional near infrared spectroscopy (fNIRS), respiration rateinformation, as well as other kinds of information related to theautonomic nervous system or other biological systems of the driver 118.

As shown within the embodiment of FIG. 1, the vehicle seat 122 can bepresented with the plurality of sensor assemblies 120 that aremechanically coupled to the vehicle seat 122 at various locations (shownas circular components disposed within the vehicle seat 122). However,it is to be appreciated, that in various embodiments, one or more sensorassemblies 120 can be disposed at different areas of the vehicle seat122 that may not be illustrated in the exemplary embodiment of FIG. 1.For example, the plurality of sensor assemblies 120 can be disposed at arear portion 126 of the vehicle seat 122, a front portion 128 of thevehicle seat 122, and (inner) side portions 130 of the vehicle seat 122.

In an exemplary embodiment, the vehicle seat 122 can include a headrest132, a seat back 134, and a seat base 136, although other configurationsof the vehicle seat 122 are contemplated. As shown in the illustratedembodiment of FIG. 1, the plurality of sensor assemblies 120 can bemechanically coupled to the vehicle seat 122 as disposed within theheadrest 132, the seat back 134, and the seat base 136. It is understoodthat the plurality of sensor assemblies 120 can any number of assemblies(e.g., two, three or more) and can be positioned in different locationsand configurations within the vehicle seat 122. In some embodiments, theplurality of sensor assemblies 120 are positioned in locationsdetermined to be best suited for sensing physiological data,contact-based surface motion data, and/or non-contact based motion datathat is associated with the driver 118.

In one or more embodiments, the plurality of sensor assemblies 120disposed within the vehicle seat 122 can be mechanically coupled to acommon structural coupling material that allows for distribution ofnoise (e.g., engine noise, road noise, road vibration, driver movement,etc.) equally to all of the sensor assemblies 120. The mechanicalcoupling of the plurality of sensor assemblies 120 can reduce theeffects of motion artifacts, since artifacts are distributed to impacteach of the sensor assemblies 120 equally.

In some embodiments, the plurality of sensor assemblies 120 can bedisposed in any portion of the vehicle 102. For example, a seat belt138, floor board 140, steering wheel 142, dashboard 144, rear-viewmirror 146, etc. can include one or more sensor assemblies 120 thatinclude different types of sensor assembly sensors (e.g., optical,visual, capacitive sensors, electrodes, etc.). Moreover, in some cases,one or more sensor assemblies 120 can be included within one or morewearable devices (not shown) worn by the driver 118. The wearabledevices can include, but are not limited to, wearable rings, watches,eye glasses, and articles of clothing. In other embodiments, one or moresensor assemblies 120 can be included with a portable device (not shown)located in proximity to the driver 118 such as a smart phone or similardevice, or associated with an article of clothing worn by the driver118.

The vehicle 102 can additionally include the one or more vehicle sensors148. The vehicle sensors 148 can include sensors associated with one ormore vehicle systems 124 and/or other components of the vehicle 102. Thevehicle sensors 148 can sense and measure a stimulus (e.g., a signal, aproperty, a measurement, or a quantity) associated with the vehicle 102and/or one or more particular vehicle systems 124. In some embodiments,the vehicle sensors 148 can also sense and measure a stimulus associatedwith the driver 118, as described in more detail below. The vehiclesensors 148 can output one or more data signals representing one or morestimulus from the vehicle sensors 148. The vehicle sensors 148 can bedisposed at various locations within a passenger cabin of the vehicle102, including, but not limited to a head unit (not shown), the floorboard 140, the dashboard 144, etc. Additionally, vehicle sensors 148 canbe located at exterior portions of the vehicle 102 such as side viewmirrors (not shown), door panels (not shown), front and rear bumpers(not shown), vehicle wheels (not shown), vehicle engine (not shown),etc.

In particular, the one or more vehicle sensors 148 (not all individuallyshown) can include, but are not limited to, an accelerometer, amagnetometer, a gyroscope, an ambient light sensor, a proximity sensor,a global positioning sensor system, a lateral acceleration sensor, andthe like. Additionally, vehicle sensors 148 can include, but are notlimited to a vehicle speed sensor, a steering angle sensor, acceleratorpedal sensor, a brake sensor, a throttle position sensor, a wheelsensor, a camshaft sensor, an electronic parking sensor, among others.The vehicle sensors 148 can also include visual sensors in the form ofcameras 150 mounted to the interior of the vehicle 102 and cameras,radar sensors, and laser sensors mounted to the exterior of the vehicle102. Further, vehicle sensors 148 can include sensors located externalto the vehicle 102 and accessed, for example, via a network. Thesesensors can include external cameras, radar and laser sensors on othervehicles in a vehicle-to-vehicle network, street cameras, surveillancecameras, blind spot indicator system, lane keep assist system, amongothers.

In an exemplary embodiment, one or more vehicle systems 124 (not allindividually shown), discussed above can include, a data storagemechanism (e.g., memory) for storing data utilized by said vehiclesystems 124, for example, sensitive data such as contact data, routedata, password data, driver behavior profiles, driver physiological dataprofiles, among others.

The vehicle sensors 148 and vehicle systems 124 can provide vehicle datato the computing device 104 that can be utilized to determine variousmetrics with respect to the driver 118 and the vehicle 102.Specifically, vehicle data can include driver and/or vehicle conditions,states, statuses, behaviors, and associated information. As discussed indetail below, in an exemplary embodiment, the vehicle sensors 148 andvehicle systems 124 can capture one or more artifacts and can outputrespective signals that are associated with the movement of the driver118 and/or the vehicle 102.

II. Processing a PPG Measurement Signal Associated with the Driver

Referring again to FIG. 2A, a schematic view of an optical sensor 202 isillustrated according to an exemplary embodiment. As discussed above,one or more of the sensor assemblies 120 includes the optical sensor202. The optical sensor 202 can be configured to emit a plurality oflight sources (near-Infrared, Infrared, laser, etc.) at a plurality offrequencies to capture and measure various signals that representsphysiological data associated to the driver 118. The optical sensor 202is also configured to increase or decrease an intensity of light emittedfrom the plurality of light sources in order to emit a plurality ofwavelengths based on the location of the optical sensor 202 and the typeof measurement that is output by the optical sensor 120.

In an exemplary embodiment, one or more optical sensors 202 areconfigured to emit a near-infrared or infrared LED light source in orderto read and measure PPG signals of the driver 118 and/or occupants ofthe vehicle 102. The one or more optical sensors 202 can be configuredto provide a volumetric measurement of the driver's blood volume andblood composition to determine metrics relating to the driver's bloodoxygen levels that can have an effect on the driver's heart rate.Specifically, the one or more optical sensors 202 can utilize pulseoximetry that provides a reflected PPG measurement of the absorption ofvarious wavelengths of infrared or near-infrared light by tissue withinthe driver's body. The one or more optical sensors 202 can each measurethe amount of light that is reflected by the tissue in order todetermine an amount of light that is absorbed by the driver's body. Inother words, the optical sensors 202 can measure the pulsation change inthe driver's blood volume with respect to oxygen saturation as moreblood will absorb a higher amount of light, and less blood will absorb alesser amount of light.

In an exemplary embodiment, each optical sensor 202 is located withinone or more sensor assemblies 120 that are disposed within the(driver's) vehicle seat 122 and other locations within the vehiclecabin. The plurality of sensor assemblies 120 can be specificallypositioned in areas that are situated to contact or not contact thesurface of the driver's skin and/or clothing in order for the opticalsensors 202 to clearly measure the driver's PPG signals. For example,one or more sensor assemblies 120 can be disposed at areas of thevehicle seat 122 and/or the vehicle 102 that are located near areas ofthe driver's body that have thinner layers of skin (e.g., ear lobes,finger tips). Additionally, one or more sensor assemblies 120 may bedisposed at areas that are near areas of the driver's body that havethick blood vessels (e.g., back, thighs).

In one embodiment, the optical sensor 202 can include source circuitry204 and detector circuitry 206. Specifically, the source circuitry 204can include the near-infrared or infrared LED light source and/or alaser light source, etc. that emits light toward various areas of thedriver's body as the driver 118 is seated within the vehicle seat 122.More particularly, the source circuitry 204 can include a plurality ofLED and laser light sources (not shown) that are configured to providevarious light colors and intensities. For example, the plurality of LEDlight sources can emit light with different wavelengths (e.g., 660-1600nm) and different frequencies (430 THz-300 GHz) that illuminate throughthe driver's skin. The source circuitry 204 of each of the opticalsensors 202 can be configured to increase or decrease the intensity ofemitted light in order to emit a plurality of wavelengths based on thelocation of the optical sensor(s) 202 and the type of measurement thatis being output by the optical sensor(s) 202. For example, with respectto the location of the optical sensors 202, the source circuitry 204 canutilize shorter wavelengths of light at areas where the optical sensors202 are located that emit light where the driver 118 is expected to bewearing clothing (e.g., back, sides) as oppose to areas where light cantypically be emitted directly to the driver's skin (e.g., neck, hands).In some embodiments, the source circuitry 204 can calibrate theintensity of various types of light by initially emitting less intenselonger wavelengths that can be used to capture one or more measurementssuch as PPG signals on skin. The source circuitry 204 can thenincrementally modify the intensity of the light wavelengths in order topenetrate through the driver's clothing to allow for the interrogationof blood vessels. In some embodiments, the intensity of light can alsobe influenced by the opacity of the driver's skin. For example, theeffect of the driver's skin color can be utilized as a factor to modifythe intensity of the LED light source during calibration by the sourcecircuitry 204.

In one or more embodiments, the detector circuitry 206 can include aphotodiode that can be configured to read an amount of scattered lightthat is transmitted through blood perfused tissue and measured on theopposite side of the tissue as the light provided by the sourcecircuitry 204 and/or reflected back to the same side of the tissue asthe light provided by the source circuitry 204. In some embodiments, thedetector circuitry 206 can include one or more cameras (in lieu of or inaddition to the photodiode) that are configured to capture images inorder to analyze and provide measurements with respect to thetransmitted light and/or the reflected light. In some configurations,the detector circuitry 206 can be positioned in order to measure one ormore paths of light from the light source(s) of the source circuitry 204that reflects back the source circuitry 204. Upon reading the amount ofscattered light that is reflected back to the detector circuitry 206,each optical sensor 202 can provide a representation of its reading inthe form of one or more PPG waveform signals. In alternateconfigurations, the detector circuitry 206 can be positioned in order tomeasure one or more paths of light from the light source(s) of thesource circuitry 204 that pass through the tissue. Upon reading theamount of scattered light that passes through the tissue to the detectorcircuitry 206, each optical sensor 202 can provide a representation ofits reading in the form of one or more PPG waveform signals.

In an exemplary embodiment, one or more optical sensors 202 can eachoutput a respective PPG waveform signal (not shown) to the PPGdeterminant module 112 within a predetermined frequency of time (e.g.,10 ms). Each PPG waveform signal output by each of the optical sensors202 can include a plurality of signal segments (not shown). The signalsegments can include the measurement of PPG signals of the driver 118along with artifacts caused by driver and vehicle movement that have aneffect on the reading of the PPG signals by the optical sensor 202.Accordingly, in some situations, the PPG waveform signals output by theone or more of optical sensors 120 can be contaminated by the artifactsand can provide skewed PPG signals. Additionally, each PPG waveformsignal can include signal features (not shown) such as signal peaks thatcan be further evaluated to determine PPG signal measurements and noisemeasurements. Additional signal features that can be evaluated includefrequency, time duration, wave amplitude, among others. It isappreciated that other characteristics of the PPG waveform signal canalso be identified as a signal feature.

FIG. 2B is a schematic representation of an exemplary PPG measurementsignal 208, a noise measurement signal 210, and a refined PPG signal 212according to an exemplary embodiment illustrates an exemplary PPGmeasurement signal 208. The PPG determinant module 112 can utilizevarious methods to process the PPG measurement signal 208 that caninclude an aggregated measurement of the driver's blood volume and bloodcomposition. Processing completed by the PPG determinant module 112generally includes converting a single PPG waveform signal oraggregating a plurality of PPG waveform signals into the PPG measurementsignal 208. Processing can include amplification, mixing, and filteringof the plurality of PPG waveform signals, as well as other signalprocessing techniques known in the art (discussed in more detail below).

Each PPG measurement signal 208 can include a plurality of signalsegments 214 (only one signal segment 214 is shown). It is to beappreciated that one or more signal segments 214 can include any sizeand/or portion of the PPG measurement signal 208. The signal segments214 can include the measurement of PPG signals of the driver 118(compiled from one or more PPG waveform signals) along with artifactscaused by driver and vehicle movement. Additionally, each PPGmeasurement can include signal features such as signal peaks 216 thatcan be further evaluated to determine PPG signal measurements and noisemeasurements. Additional signal features that can be evaluated includefrequency, time duration, wave amplitude, local maximum and minimumpoints, and inflection points (related to the second derivative of PPG)among others (not shown). It is appreciated that other characteristicsof the PPG measurement signal 208 can also be identified as a signalfeature.

Referring now to FIG. 3, a process flow diagram of an exemplary method300 for processing a PPG measurement signal 208 from the one or more PPGwaveform signals is shown according to an exemplary embodiment. FIG. 3will be described with reference to the systems/components/illustrationsof FIG. 1, FIG. 2A, and FIG. 2B, though it is to be appreciated that themethod of FIG. 3 can be used with other systems/components. In someembodiments, some or all of the steps of the method 300 can be preformedby the PPG determinant module 112. In other embodiments, other modulescan perform some or all of the steps described with the method 300.

At block 302, the method includes receiving one or more PPG waveformsignals. In one embodiment, the PPG determinant module 112 communicateswith one or more sensor assemblies 120 that are disposed at variousareas of the vehicle seat 122 and/or the vehicle 102 in order to receivethe one or more PPG waveform signals that are output by the one or moreof optical sensors 202. Upon receipt of the one or more PPG waveformsignals, the PPG determinant module 112 can store data pertaining to thesignal features of the one or more PPG waveform signals onto the memory108 and/or the disk 110 of the computing device 104 in order to befurther evaluated.

At block 304, the method includes evaluating the one or more PPGwaveform signals in order to determine the most consistent PPG waveformsignals. In one embodiment, the PPG determinant module 112 accesses datapertaining to the signal features of the one or more PPG waveformsignals from the memory 108 and/or the disk 110 and can determine one ormore PPG waveform signals that include similar waveform patterns basedon one or more signal features that are within one or more determinedmean signal feature categories. More specifically, the PPG determinantmodule 112 can evaluate signal features of each of the PPG waveformsignals including frequency, time duration, wave amplitude, measurementbetween signal peaks, local maximum and minimum points, and inflectionpoints (related to the second derivative of PPG), etc. Upon evaluatingthe signal features, the PPG determinant module 112 can determinemeasurement values associated with each of the signal features (e.g.,distance/time measurements) in order to compute mean values associatedto each of the signal features.

Upon determining mean values associated to each of the signal features,the PPG determinant module 112 can determine one or more signal featurecategories associated with each of the signal features. The one or moresignal feature categories can include a categorization of the signalfeatures of the one or more PPG waveform signals that are within apredetermined range from the mean signal feature value. For example, amean signal feature category can include a peak signal measurementcategory that includes a predetermined range of values that are within arange from a mean value of a measurement between peak signals of each ofthe plurality of waveform signals. The PPG determinant module 112 canfurther evaluate PPG waveform signals that include signal features thatfall within a predetermined amount of signal feature categories in orderto determine the most consistent PPG waveform signals. It is to beappreciated that the PPG determinant module 112 can utilize variousother methods to evaluate the one or more PPG waveform signals in orderto determine the most consistent PPG waveform signals

By determining the most consistent PPG waveform signals, the PPGdeterminant module 112 can capture the most accurate representation ofthe driver's PPG signals that have been captured from the vehicle seat122 and/or the vehicle 102. For example, the PPG determinant module 112can evaluate ten PPG waveform signals provided by ten optical sensors202 in order to determine three PPG waveform signals that include signalfeatures that include values that fall within the predetermined amountof signal feature categories.

At block 306, the method includes discarding inconsistent PPG waveformsignals. In one embodiment, the PPG determinant module 112 removes theinconsistent PPG waveform signals stored on the memory 108 and/or thedisk 110 in order ensure such data does not influence the measurement ofthe driver's PPG signals. Specifically, the PPG determinant module 112removes PPG waveform signals that are not determined to fall within thepredetermined amount of signal feature categories. In particular, bydiscarding the inconsistent PPG signal waveforms 208 based on theevaluation conducted at block 304, the PPG determinant module 112ensures that optical sensors 202 that are located in areas of thevehicle seat 122 and/or the vehicle 102 from which PPG readings may nothave been completely or accurately captured are not accounted for whenprocessing the PPG measurement signal 208.

At block 308, the method includes aggregating the most consistent PPGwaveform signals and outputting a PPG measurement signal 208. In anexemplary embodiment, the PPG determinant module 112 aggregates the mostconsistent PPG waveform signals as determined at block 304 into the PPGmeasurement signal 208 that represents the most consistent measurementof the driver's PPG signals.

With reference again to FIG. 1, FIG. 2A, and FIG. 2B, in anotherembodiment, the PPG determinant module 112 can determine an optimum PPGwaveform signal (not shown) that is selected out of the plurality of PPGwaveform signals output by the plurality of optical sensors 202. Theoptimum PPG waveform signal can be determined by the PPG determinantmodule 112 to be the most accurate measurement of the driver's PPGsignals. In one embodiment, the PPG determinant module 112 can determinethe optimum PPG waveform signal by determining the PPG waveform signalthat is output by the optical sensor 202 that emits the lowest amount ofLED light intensity in order to capture the driver's PPG signals. Inother words, the optimum PPG waveform signal is determined to be the PPGwaveform signal that is most likely to be captured closer to thedriver's skin, thereby ensuring minimal interference by the driver'sclothing or the space between the sensor and the driver 118.

In another embodiment, the PPG determinant module 112 can determine theoptimum PPG waveform signal by communicating with one or more pressuresensors included within the one or more sensor assemblies 120 in orderto determine the pressure sensor that measures the highest pressuremeasurement caused by the driver 118 seated within the vehicle seat 122.In particular, one more sensor assemblies 120 that include the pressuresensor(s) can be disposed at particular locations of the vehicle seat122 in which the change in pressure caused by the driver 118 isdetected. The pressure sensor(s) can communicate pressure measurementdata to the PPG determinant module 112 with respect to which pressuresensor measures the highest pressure measurement caused by the driver118 in order to determine the optimum PPG waveform signal. In otherwords, the optimum PPG waveform signal is determined to be the PPGwaveform signal that is most likely to be captured by an optical sensor202 included within the sensor assembly 120 that is determined to be ata location of the vehicle seat 120 that is most utilized by the driver118 (i.e., a location where a consistent/constant measurement can takeplace). Upon determining the optimum PPG waveform signal, the PPGdeterminant module 112 can convert the optimum PPG waveform signal intothe PPG measurement signal 208.

In additional embodiments, the PPG signal determinant module 112 canprocess the PPG measurement signal 208 by separately evaluating PPGwaveform signals that are captured from respective areas of the vehicleseat 122 in order to determine the optimum PPG waveform signal capturedfrom each area of the vehicle seat 122. For example, the PPG determinantmodule 112 can determine four optimum PPG waveform signals captured bythe optical sensors 202 located at the each of the seat back 134, andthe seat base 136. Upon determining the optimum PPG waveform signals,the PPG determinant module 112 can aggregate the optimum PPG waveformsignals captured from each area of the vehicle seat 122 into the PPGmeasurement signal 208. It is to be appreciated that the PPG determinantmodule 112 can utilize various other methods to process the PPGmeasurement signal 208 from one or more PPG waveform signals provided bythe plurality of optical sensors 202.

As discussed above, the PPG waveform signals can be contaminated withmotion artifacts caused by the driver 118 and/or the vehicle 102.Therefore, one or more signal segments 214 of the PPG measurement signal208 that is processed by the PPG determinant module 112 also includesmotion artifacts. Accordingly, the PPG determinant module 112 sends theprocessed PPG measurement signal 208 to the PPG signal filtering module116 in order filter the motion artifacts and extract a refined PPGsignal 212.

Apart from being configured to read and measure PPG signals of thedriver 118, as discussed above, the plurality of optical sensors 202 canalso emit a plurality of light sources at a plurality of frequencies inorder to read signals that are associated with additional physiologicaldata related to the driver 118 and/or occupants of the vehicle 102. Forexample, the optical sensors 202 can emit signals to determine physicalinformation related to the driver 118 and/or occupants includingbiometric identification of the driver 118 and/or occupants based onsensing signals associated to physical characteristics (e.g., posture,position, movement) and biological characteristics (e.g., bloodpressure, blood flow, oxygen content in the blood, etc.).

In one embodiment, the optical sensors 202 can emit the plurality oflight sources at the plurality of frequencies in order to non invasivelymeasure the driver's and/or occupant's blood alcohol levels. Forexample, the source circuitry 204 of the optical sensors 202 can emitlight into the driver's skin. The optical sensors 202 can measure atissue alcohol concentration based on the amount of light that isreflected back by the skin to the detector circuitry 206. Additionally,the optical sensors 202 can noninvasively monitor a condition of thedriver 118 through the determination of biological signals, such asbody-trunk plethysmograph and respiration that are detected from thedriver's back from one or more optical sensors 202 included withinsensor assemblies 120 disposed at the seat back 134 of the vehicle seat122. In particular, one or more filtered signals can be evaluated todetermine the driver's PPG signals that fall between normal andintoxicated states in order to determine driver intoxication. Such atechnique is described by K. Murata, et. al in “Noninvasive BiologicalSensor System for Detection of Drunk Driving,” IEEE Transactions onInformation Technology in Biomedicine, Vol. 15, No, 1, 2011, the entirecontents of which are incorporated by reference.

In an additional embodiment, the optical sensor 202 can emit variouslight sources in order to non invasively identify the driver 118 and/oroccupant(s) of the vehicle 102 via biometric identification. Forexample, one or more physiological signals (e.g., PPG signals, etc.) canbe measured by the optical sensors 202 in order to determinephysiological signals that can be matched against a database of enrolledbiometric templates. The database of enrolled biometric templates caninclude a biometric template from the driver 118 and/or occupants of thevehicle 102. Examples of biometric identification techniques aredescribed within the parent application of the present application.Additional, exemplary biometric techniques are described by A. Re

it Kaysao{hacek over (g)}lu et. al in “A novel feature ranking algorithmfor biometric recognition with PPG signals,” Computer in Biology andMedicine, Vol. 49, 2014, 1-14, and as well as Agrafito et al. filed May10, 2012, the entirety of both being hereby incorporated by reference.

III. Processing a Motion Artifacts Measurement Signal Associated withthe Driver and the Vehicle

Referring back to FIG. 1 and FIG. 2B, several techniques to determinemotion artifacts associated to the driver 118 and the vehicle 102 willnow be described. In an exemplary embodiment, the motion artifactdeterminant module 114 can communicate with one or more sensor assemblysensors, one or more vehicle sensors 148, and/or one or more vehiclesystems 124 in order to determine motion artifacts associated with thedriver 118 seated within the vehicle seat 122 and/or the vehicle 102itself as it is being driven by the driver 118.

In an exemplary embodiment, data can be provided by various types ofseat assembly sensors, vehicle sensors 148, and/or vehicle systems 124in the form of one or more noise waveform signals (not shown) that areoutput within a predetermined frequency of time (e.g., 10 ms) to themotion artifact determinant module 114. As discussed below, the motionartifact determinant module 114 can convert one noise waveform signal oraggregate a plurality of noise waveform signals output by a plurality ofsensor assembly sensors, vehicle sensors 148, and vehicle systems 124into the motion artifacts measurement signal 210.

Some exemplary embodiments utilizing specific types of sensor assemblysensors, vehicle sensors 148, and vehicle systems 124 to determinemotion artifacts associated with the driver 118 and the vehicle 102 willnow be discussed below with reference to FIG. 1, FIG. 2A, and FIG. 2B.However, it is to be appreciated, that sensors not specificallydisclosed within the exemplary embodiments discussed below may also beutilized alone or in combination with one another to determine themotion artifacts measurement signal 210.

In one or more embodiments, the optical sensor 202 can emit a blue/nearUV visible light source that is configured to emit light towards thesurface of the driver's skin. In particular, the blue/near UV visiblelight source can be configured to increase or decrease the intensity ofemitted light in order to emit a plurality of wavelengths based on thelocation of the optical sensor 202 with respect to the driver 118. Forexample, the blue/near UV visible light source can emit a shorterwavelength of light at areas where the driver 118 is expected to bewearing clothing (e.g., back, sides) as oppose to areas where light cantypically be transmitted directly to the driver's skin (e.g., neck,hands). The detector circuitry 206 of the optical sensor 202 candetermine a reflectance of light that is absorbed by the surface of thedriver's skin in order to determine the driver's movements within thevehicle seat 122. One or more optical sensors 202 can output one or moreof noise waveform signals that are indicative of the driver's movementswithin the vehicle seat 122.

In one or more embodiments, seat assembly sensors including, but notlimited to, accelerometers (not shown), gyroscopes (not shown),proximity detectors (not shown), magnetometers (not shown), etc., can beutilized alone or in combination to output one or more noise waveformsignals to the motion artifact determinant module 114. In oneembodiment, one or more accelerometers included within one or moresensor assemblies 120 can determine motion artifacts associated to thedriver 118. In particular, the one or more accelerometers cancommunicate data that is indicative of the driver's movement within thevehicle seat 122. In some embodiments, the one or more accelerometerscan be positioned atop the optical sensor 202, each orientedperpendicular to each other in order to capture motion artifacts thatcan most directly disturb the measurement of the driver's PPG signals bythe optical sensor 202. Specifically, the one or more accelerometers canalso include capacitive accelerometers that are used to determine andmeasure changes in a degree of movement of the driver 118 within thevehicle seat 122. For example, as the driver 118 accelerates and brakesthe vehicle 102, the accelerometer(s) can determine a rate of change ofthe movement of the driver 118 as the driver 118 may shift back andforth within the vehicle seat 122.

Additionally, in some embodiments, the one or more pressure sensorsincluded within the one or more sensor assemblies 120, discussed above,can be utilized to determine motion artifacts associated to the driver118. In particular, one more sensor assemblies 120 that include thepressure sensor(s) can be disposed at particular locations of thevehicle seat 122 in which the driver's movement can be determined basedon the change in pressure as the driver 118 moves within the vehicleseat 122. The pressure sensor(s) can include hardware configured todetermine movement of the driver 118 based on the change in pressure asdetected by the shifting of the driver's weight within the vehicle seat122. For example, one or more pressure sensors located within the seatback 134 of the vehicle seat 122 can determine and measure a change inmovement of the driver 118 whose weight distributes away and toward theseat back 134 as the driver 118 moves forward or backward within thevehicle seat 122. The pressure sensor(s) can output one or more noisewaveform signals to the motion artifacts determinant module 114.

In an additional embodiment, one or more vibration sensors (not shown)included within the one or more sensor assemblies 120 and/or vehiclesensors 148 can also be utilized to determine motion artifactsassociated to the driver 118 and/or the vehicle 102. The one or morevibration sensors can include piezoelectric sensors for detectingmechanical vibrations associated to the vehicle seat 122 and/or thevehicle 102. For example, the one or more vibration sensors can sensevibrations that can be attributed to the engine, the roadway on whichthe vehicle 102 is being driven, and/or the driver's movement within thevehicle seat 122. The vibration sensor(s) can output one or more noisewaveform signals to the motion artifacts determinant module 114.

In some embodiments, one or more proximity sensors (not shown) includedwithin the one or more sensor assemblies 120 and/or vehicle sensors 148can also be utilized to determine motion artifacts associated with thedriver 118 and/or the vehicle 102. For example, a plurality of proximitysensors can be operable to determine the location of the driver 118 ashe or she moves within the vehicle seat 122. Specifically, eachproximity sensor can output a proximity measurement based on theproximity of the driver 118 to the respective sensor. The proximitysensor(s) can output one or more noise waveform signals to the motionartifacts determinant module 114.

In an alternate embodiment, one or more wearable devices can be worn bythe driver 118 that can also measure the driver's movement within thevehicle seat 122. The wearable device(s) can include one or moremovement tracking sensors (e.g., accelerometer, gyroscope, etc.). Thewearable device(s) can include device logic that is configured to trackand measure movements of the driver 118 wearing the wearable device(s).The wearable device(s) can output one or more noise waveform signals tothe motion artifacts determinant module 114.

In some embodiments, the (internal) cameras 150 included as part of thevehicle sensors 148 can be located throughout the vehicle 102.Specifically, one or more cameras 150 can be positioned in various areasin front of, above, and/or around the vehicle seat 122 in order tocapture real time images of the driver 118 as the vehicle 102 is beingdriven. The one or more cameras 150 can include hardware configured tointerpret video or image data sensed by the camera(s) 150 to recognizeany movement associated with the driver 118 within the vehicle seat 122.In one embodiment, the processor 106 can include camera logic that canevaluate image data output by one or more cameras 150 and can compilethe image data to determine and measure changes in the movement of thedriver 118 within the vehicle seat 122. The compiled data can beprovided to the motion artifact determinant module 114 in the form ofone or more noise waveform signals.

Additional vehicle sensors 148 can be used in conjunction with oneanother to provide data regarding body movement of the vehicle 102 asthe vehicle 102 is being driven on a roadway. For example, vehiclesensors 148 disposed at each wheel of the vehicle 102 can measure a ridelevel of the vehicle 102 and one or more accelerometers included as partof the vehicle sensors 148 can measure vertical body acceleration of thevehicle 102 in order to accurately measure road noise. The vehiclesensors 148 can also be used to determine the steering angle, roll,pitch, lateral acceleration and yaw of the vehicle 102 as an indicationof the vehicle 102 reacting to turns, acceleration, braking, and roadnoise that can affect the capturing of one or more PPG signals by theoptical sensors 202. For example, one or more vehicle sensors 148 thatinclude the steering sensor, gyroscope, lateral acceleration sensors,acceleration pedal sensors, brake sensors, wheel speed sensors, etc. canbe utilized alone or in combination with one another to output noisewaveform signals to the motion artifacts determinant module 114.

In some embodiments, one or more vehicle systems 124 can provide one ormore noise waveform signals to the motion artifacts determinant module114. For example, the electronic stability control system (not shown)can monitor the yaw rate of the vehicle 102 and can output movement datain the form of a noise waveform signal.

In an exemplary embodiment, upon receiving one or more noise waveformsignals from the sensor assembly sensors, vehicle sensors 148, and/orvehicle systems 124, the motion artifact determinant module 114 canprocess the one or more noise waveform signals into the motion artifactsmeasurement signal 210. Processing completed by the motion artifactsdeterminant module 114 generally includes converting one noise waveformsignal or aggregating the plurality of noise waveform signals into themotion artifacts measurement signal 210. Processing can includeamplification, mixing, and filtering of one or more noise waveformsignals, as well as other signal processing techniques known in the art.The motion artifacts measurement signal 210 can include signal segments(not shown) and signal features (not shown) similar to the PPGmeasurement signal 208 that are representative of motion artifactsassociated with the driver 118 and the vehicle 102.

In some embodiments, upon receiving the plurality of noise waveformsignals from the sensor assembly sensors, vehicle sensors 148, and/orvehicle systems 124, the motion artifact determinant module 114 canassign a weight to each of the received noise waveform signals. Theweight assigned to each of the noise waveform signals can be associatedto a determined level of impact that each sensed noise waveform signalhas to the motion artifacts that are contaminating the PPG measurementsignal 208. The level of impact can be determined by evaluating one ormore noise waveform signals that are output by one or more sensorassembly sensors, vehicle sensors 148, and/or vehicle systems 124. Uponevaluating the one or more noise waveform signals, the motion artifactsdeterminant module 114 can apply a respective weight to each noisewaveform signal based on the type of sensors/systems that output thenoise waveform signal, the location of the sensors/systems that outputthe noise waveform signal, the type of data that the sensors/systemsthat output the noise waveform signal are capturing/measuring, and theimpact of the noise waveform signal on the capturing of PPG waveformsignals output by one or more optical sensors 202. For example, one ormore noise waveform signals that are output by biological sensorslocated within the one or more sensor assemblies 120 within the vehicleseat 122 can be determined to have a higher level impact and cantherefore be assigned a higher weight than other noise waveform signalsprovided by non-biological sensors located at other areas of the vehicle102. Upon determining the weight of each of the noise waveform signals,the motion artifacts determinant module 114 can aggregate the pluralityof noise waveform signals to each impact the processed motion artifactsmeasurement signal 210 based on an assigned weight.

In yet another embodiment, upon receiving a plurality of noise waveformsignals, the motion artifact determinant module 114 can separatelyevaluate noise waveform signals that are attributed to movement of thedriver 118 apart from noise waveform signals that are attributed to themovement of vehicle 102 itself to determine a driver motion artifactsmeasurement signal (not shown) and a vehicle motion artifactsmeasurement signal (not shown). Specifically, the motion artifactdeterminant module 114 can aggregate the noise waveform signals that areattributed to the movement of the driver 118 into the driver motionartifacts measurement signal. Similarly, the motion artifact determinantmodule 114 can aggregate the noise waveform signals that are attributedto the movement of the vehicle 102 in the vehicle motion artifactsmeasurement signal.

It is to be appreciated that additional methods can be utilized by themotion artifact determinant module 114 in order to process the motionartifacts measurement signal 210. In an exemplary embodiment, upondetermining the motion artifacts measurement signal 210, the motionartifact determinant module 114 can send the processed motion artifactsmeasurement signal 210 to the PPG signal filtering module 116 in orderfilter the PPG measurement signal 208 and process the refined PPG signal212.

III. Processing a Refined PPG Signal and Additional Motion ArtifactResistant Techniques

The PPG signal filtering module 116 can utilize one or more techniquesto decontaminate the PPG measurement signal 208 processed by the PPGdeterminant module 112 from motion artifacts associated with the driver118 and the vehicle 102 itself. Processing completed by the PPG signalfiltering module 116 can include amplification, mixing, and filtering ofthe PPG measurement signal 208 and the motion artifacts measurementsignal 210, as well as other signal processing techniques known in theart, some of which are discussed below.

In an exemplary embodiment, upon receiving the motion artifactsmeasurement signal 210, the PPG signal filtering module 116 can apply afilter on the PPG measurement signal 208 output by the PPG determinantmodule 112 in order to process the refined PPG signal 212. The refinedPPG signal 212 is indicative of a measurement of the driver's bloodvolume and blood composition that is decontaminated from the one or moremotion artifacts associated with the driver 118 and the vehicle 102.

With reference to FIGS. 1 and 2B, when applying the filter, the PPGsignal filtering module 116 can evaluate the motion artifactsmeasurement signal 210 and PPG measurement signal 208 to process therefined PPG signal 212 that is filtered from the PPG measurement signal208. Specifically, the PPG signal filtering module 116 can determinesignal segments 214 of the PPG measurement signal 208 that include datathat is attributed to the PPG measurement signal 208 and data that isattributed to the motion artifacts measurement signal 210. In otherwords, the PPG signal filtering module 116 can determine one or moresignal segments 214 of PPG measurement signal 208 that are attributed tomotion artifacts associated with the driver 118 and the vehicle 102, asrepresented by the motion artifacts measurement signal 210.

Upon determining signal segments 214 of the PPG measurement signal 208that includes the motion artifacts, the PPG signal filtering module 116can filter one or more signal segments 214 of the PPG measurement signal208 that are attributed to the motion artifacts as represented by themotion artifacts measurement signal 210 in order to extract one or moresignal segments 214 that are representative of the refined PPG signal212. Upon extraction of the one or more signal segments 214 that arerepresentative of the refined PPG signal 212, the PPG signal filteringmodule 116 can process and output the refined PPG signal 212 (thisprocess is best illustrated by the best example as presented in FIG.2B).

In an alternate embodiment, as discussed above, the motion artifactsdeterminant module 114 can provide separate motion artifacts measurementsignals in the form of the driver motion artifacts measurement signaland the vehicle motion artifacts measurement signal that are eachindividually associated with the driver 118 and the vehicle 102. Uponreceiving the driver motion artifacts measurement signal and the vehiclemotion artifacts signal, the PPG signal filtering module 116 can applymultiple levels of filtering to the PPG measurement signal 208 in orderto filter one or more signal segments 214 of the PPG measurement signal208 that are attributed to the driver motion artifacts measurementsignal separately from one or more signal segments 214 that areattributed to the vehicle motion artifacts measurement signal. It is tobe appreciated that additional methods can be utilized by the PPG signalfiltering module 116 in order to process the refined motion artifactssignal.

In one or more embodiments, the refined PPG signal 212 can be providedby the PPG signal filtering module 116 to the processor 106 of thecomputing device 104 in order to be utilized for biometricinterpretation by one or more vehicle systems 124. Specifically, thecomputing device 104 can evaluate the refined PPG signal 212 in order todetermine biometric data that is associated with the driver 118. Thecomputing device 104 can further utilize such biometric data in order todetermine one or more driver states that can be utilized to controlvehicle HMI output, vehicle systems 124, and/or autonomous driving ofthe vehicle 102. The “driver state,” as used herein, refers to ameasurement of a state of the biological system of the driver. Thedriver state can be one or more of alert, vigilant, drowsy, inattentive,distracted, stressed, intoxicated, other generally impaired states,other emotional states and/or general health states, among others.

In alternate embodiments, alternative methods can be utilized by thesystem 100 in order to process the refined PPG signal 212. In oneembodiment, a method of signal modulation and demodulation can beutilized in order to decontaminate the PPG measurement signal 208 frommotion artifacts. More specifically, a carrier frequency can begenerated at a calculated frequency of a harmonic of an identified noisecomponent (e.g., noise waveform signal) that can be utilized to generateand demodulate an amplitude modulated signal (e.g., PPG measurementsignal 208) in order to reduce signal interference. Such a method isdescribed in Anderson et al., U.S. Pat. No. 7,623,990, filed Nov. 3,2005, the entirety of which is hereby incorporated by reference.

In another embodiment, instead of filtering the PPG measurement signal208 from the motion artifacts measurement signal 210 in order to processthe refined PPG signal 212, the system 100 can utilize methods forminimizing the influence of motion artifacts during the measurement ofPPG signals. For instance, a method of using amplitude modulated lightcan be used to encode the PPG signal (e.g., PPG waveform signals, PPGmeasurement signal 208) in order to distinguish the measured PPG signalfrom noise. In one embodiment, the source circuitry 204 of the opticalsensor 202 can generate an amplitude modulated code sequence in the formof a Barker binary code sequence that is received by the detectorcircuitry 206. The Barker binary code sequence can be used to detect thesegment of the signal associated to noise based on determining anactivated light source and deactivated light source in order todifferentiate the PPG signal from noise. Such a technique is describedby R. Gircys, et. al in “Movement Artefact ResistantPhotoplethysmographic Probe,” Elektronika IR Elektrontechnika, ISSN1392-1215, Vol. 20, 2014, the entire contents of which are incorporatedby reference.

IV. Method for Processing PPG Signals in a Vehicle

Referring now to FIG. 4, a process flow diagram of an exemplarycomputing-implemented method 400 for processing PPG signals in thevehicle 102 is provided from the operating environment of FIG. 1according to an exemplary embodiment. FIG. 4 will be described withreference to the components of FIG. 1, FIG. 2A, and FIG. 2B, though itis to be appreciated that the method of FIG. 4 can be used with othersystems/components. At block 402, the method includes receiving a PPGwaveform signal from an optical sensor. In one embodiment, as describedabove, one or more optical sensors 202 included within one or moresensor assemblies 120 can each output a respective PPG waveform signalto the PPG determinant module 112.

At block 404, the method includes processing a PPG measurement signal208 based on the PPG waveform signal. In an exemplary embodiment, uponreceiving one or more PPG waveform signals, the PPG determinant module112 can convert one PPG waveform signal (e.g., the optimum PPG waveformsignal) or aggregate the plurality of PPG waveform signals in order toprocess the PPG measurement signal 208. At block 406, the methodincludes receiving a noise waveform signal from at least one of: a seatassembly sensor, a vehicle sensor, and a vehicle system. As discussed indetail above, one or more seat assembly sensors, vehicle sensors 148,and/or vehicle systems 124 can output one or more noise waveform signalsto the motion artifacts determinant module 114.

At block 408, the method includes processing a motion artifactsmeasurement signal 210 based on the noise waveform signal. In anexemplary embodiment, upon receiving one or more noise waveform signals,the motion artifacts determinant module 114 can convert one noisewaveform signal or aggregate the plurality of noise waveform signals inorder to process the motion artifacts measurement signal 210.

At block 410, the method includes processing a refined PPG signal 212 tosuppress the motion artifacts measurement signal 210 from the PPGmeasurement signal 208. As discussed, in one embodiment, the PPG signalfiltering module 116 can receive the PPG measurement signal 208 and themotion artifacts signal respectively from the PPG determinant module 112and the motion artifact determinant module 114. The PPG signal filteringmodule 116 can filter the PPG measurement signal 208 by determining oneor more segments of the PPG measurement signal 208 that include datathat is attributed to the motion artifacts measurement signal 210. ThePPG signal filtering module 116 can filter one or more signal segments214 of the PPG measurement signal 208 that are attributed to the motionartifacts as represented by the motion artifacts measurement signal 210,in order to process the refined PPG signal 212. The refined PPG signal212 is indicative of a measurement of the driver's blood volume andblood composition that is decontaminated from the one or more motionartifacts associated with the driver 118 and the vehicle 102.

The embodiments discussed herein may also be described and implementedin the context of non-transitory computer-readable storage mediumstoring computer-executable instructions. Non-transitorycomputer-readable storage media includes computer storage media andcommunication media. For example, flash memory drives, digital versatilediscs (DVDs), compact discs (CDs), floppy disks, and tape cassettes.Non-transitory computer-readable storage media may include volatile andnonvolatile, removable and non-removable media implemented in any methodor technology for storage of information such as computer readableinstructions, data structures, modules or other data. Non-transitorycomputer readable storage media excludes transitory and propagated datasignals.

It will be appreciated that various embodiments of the above-disclosedand other features and functions, or alternatives or varieties thereof,may be desirably combined into many other different systems orapplications. Also that various presently unforeseen or unanticipatedalternatives, modifications, variations, or improvements therein may besubsequently made by those skilled in the art which are also intended tobe encompassed by the following claims.

The invention claimed is:
 1. A computer-implemented method forprocessing photoplethysmography (PPG) signals in a vehicle, comprising:receiving a plurality of PPG waveform signals from a plurality ofoptical sensors; processing a PPG measurement signal based on theplurality of PPG waveform signals, wherein processing the PPGmeasurement signal includes aggregating the plurality of PPG waveformsignals that are received from the plurality of optical sensors into thePPG measurement signal; receiving a noise waveform signal from at leastone of: a seat assembly sensor, a vehicle sensor, and a vehicle system;processing a motion artifacts measurement signal based on the noisewaveform signal; processing a refined PPG signal to suppress the motionartifacts measurement signal from the PPG measurement signal, whereinprocessing the refined PPG signal includes filtering a segment of thePPG measurement signal that is attributed to motion artifactsrepresented within the motion artifacts measurement signal; anddetermining at least one driver state associated with a driver of thevehicle based on the refined PPG signal and controlling at least onevehicle system of the vehicle based on the driver state associated withthe driver.
 2. The computer-implemented method of claim 1, wherein theplurality of optical sensors are included within at least one sensorassembly that is mechanically coupled to a vehicle seat in the vehicle.3. The computer-implemented method of claim 2, wherein receiving theplurality of PPG waveform signals from the plurality of optical sensorsincludes the plurality of optical sensors emitting a plurality of lightsources at a plurality of frequencies, wherein the plurality of opticalsensors is also configured to increase or decrease the intensity oflight emitted from the plurality of light sources in order to emit aplurality of wavelengths based on the location of the plurality ofoptical sensors and the type of measurement that is being output by theplurality of optical sensors.
 4. The computer-implemented method ofclaim 1, wherein processing the PPG measurement signal includesaggregating the plurality of PPG waveform signals that represent aconsistent measurement of PPG readings associated with the driver,wherein at least one PPG waveform signal is discarded that is determinedto be inconsistent with the plurality of PPG waveform signals.
 5. Thecomputer-implemented method of claim 1, wherein processing the PPGmeasurement signal includes determining an optimum PPG waveform signaland converting the optimum PPG waveform signal into the PPG measurementsignal, wherein the optimum PPG waveform signal is determined to be aPPG waveform signal of the plurality of PPG waveform signals that isoutput by the plurality of optical sensors that emits a lowest amount ofLED light intensity.
 6. The computer-implemented method of claim 1,wherein processing the motion artifacts measurement signal includesaggregating a plurality of noise waveform signals received from at leastone of: the seat assembly sensor, the vehicle sensor, and the vehiclesystem into the motion artifacts measurement signal.
 7. Thecomputer-implemented method of claim 6, wherein aggregating theplurality of noise waveform signals includes assigning a weight to eachnoise waveform signal received from at least one of: the seat assemblysensor, the vehicle sensor, and the vehicle system, and aggregating theplurality of noise waveform signals to each impact the motion artifactsmeasurement signal based on an assigned weight.
 8. Thecomputer-implemented method of claim 1, wherein processing the refinedPPG signal includes filtering the PPG measurement signal, whereinfiltering the PPG measurement signal includes determining a segment ofthe PPG measurement signal that includes data that is attributed to themotion artifacts measurement signal, filtering the segment of the PPGmeasurement signal that is attributed to the motion artifacts asrepresenting the motion artifacts measurement signal, and outputting therefined PPG signal, wherein the refined PPG signal is indicative of ameasurement of the driver's blood volume and blood composition that isdecontaminated from the one or more motion artifacts associated with thedriver of the vehicle and the vehicle.
 9. A system for processingphotoplethysmography (PPG) signals in a vehicle, comprising: a memorystoring instructions when executed by a processor cause the processorto: receive a plurality of PPG waveform signals from a plurality ofoptical sensors; process a PPG measurement signal based on the pluralityof PPG waveform signals, wherein processing the PPG measurement signalincludes aggregating the plurality of PPG waveform signals that arereceived from the plurality of optical sensors into the PPG measurementsignal; receive a noise waveform signal from at least one of: a seatassembly sensor, a vehicle sensor, and a vehicle system and processes amotion artifacts measurement signal based on the noise waveform signal;process a refined PPG signal to suppress the motion artifactsmeasurement signal from the PPG measurement signal, wherein processingthe refined PPG signal includes filtering a segment of the PPGmeasurement signal that is attributed to motion artifacts representedwithin the motion artifacts measurement signal; and determine at leastone driver state associated with a driver of the vehicle based on therefined PPG signal and control at least one vehicle system of thevehicle based on the driver state associated with the driver.
 10. Thesystem of claim 9, wherein the plurality of optical sensors are includedwithin at least one sensor assembly that is mechanically coupled to avehicle seat in the vehicle.
 11. The system of claim 10, wherein theplurality of optical sensors is configured to emit a plurality of lightsources at a plurality of frequencies, wherein the plurality of opticalsensors is also configured to increase or decrease the intensity oflight emitted from the plurality of light sources in order to emit aplurality of wavelengths based on the location of the plurality ofoptical sensors and the type of measurement that is being output by theplurality of optical sensors.
 12. The system of claim 9, whereinprocessing the PPG measurement signal includes aggregating the pluralityof PPG waveform signals that represent a consistent measurement of PPGreadings associated with the driver, wherein at least one PPG waveformsignal is discarded that is determined to be inconsistent with theplurality of PPG waveform signals.
 13. The system of claim 9, whereinprocessing the PPG measurement signal includes determining an optimumPPG waveform signal and converting the optimum PPG waveform signal intothe PPG measurement signal, wherein the optimum PPG waveform signal isdetermined to be a PPG waveform signal of the plurality of PPG waveformsignals that is output by the plurality of optical sensors that emits alowest amount of LED light intensity.
 14. The system of claim 9, whereinprocessing the motion artifacts measurement signal includes aggregatinga plurality of noise waveform signals received from at least one of: theseat assembly sensor, the vehicle sensor, and the vehicle system intothe motion artifacts measurement signal.
 15. The system of claim 14,wherein aggregating the plurality of noise waveform signals includesassigning a weight to each noise waveform signal received from at leastone of: the seat assembly sensor, the vehicle sensor, and the vehiclesystem, wherein the motion artifacts determinant module aggregates theplurality of noise waveform signals to each impact the motion artifactsmeasurement signal based on an assigned weight.
 16. The system of claim9, wherein processing the refined PPG signal includes filtering the PPGmeasurement signal, wherein filtering the PPG measurement signalincludes determining a segment of the PPG measurement signal thatincludes data that is attributed to the motion artifacts measurementsignal, filtering the segment of the PPG measurement signal that isattributed to the motion artifacts as representing the motion artifactsmeasurement signal, and outputting the refined PPG signal, wherein therefined PPG signal is indicative of a measurement of the driver's bloodvolume and blood composition that is decontaminated from the one or moremotion artifacts associated with the driver of the vehicle and thevehicle.
 17. A non-transitory computer readable storage medium storinginstructions that when executed by a computer, which includes aprocessor perform a method comprising: receiving a plurality of PPGwaveform signals from a plurality of optical sensors; processing a PPGmeasurement signal based on the plurality of PPG waveform signals,wherein processing the PPG measurement signal includes aggregating theplurality of PPG waveform signals that are received from the pluralityof optical sensors into the PPG measurement signal; receiving a noisewaveform signal from at least one of: a seat assembly sensor, a vehiclesensor, and a vehicle system; processing a motion artifacts measurementsignal based on the noise waveform signal; processing a refined PPGsignal to suppress the motion artifacts measurement signal from the PPGmeasurement signal, wherein processing the refined PPG signal includesfiltering a segment of the PPG measurement signal that is attributed tomotion artifacts represented within the motion artifacts measurementsignal; and determining at least one driver state associated with adriver of the vehicle based on the refined PPG signal and controlling atleast one vehicle system of the vehicle based on the driver stateassociated with the driver.
 18. The computer readable storage medium ofclaim 17, wherein receiving the plurality of PPG waveform signals fromthe plurality of optical sensors includes the plurality of opticalsensors emitting a plurality of light sources at a plurality offrequencies, wherein the plurality of optical sensors is also configuredto increase or decrease the intensity of light emitted from theplurality of light sources in order to emit a plurality of wavelengthsbased on the location of the plurality of optical sensors and the typeof measurement that is being output by the plurality of optical sensors.19. The computer readable storage medium of claim 17, wherein processingthe PPG measurement signal includes aggregating the plurality of PPGwaveform signals that represent a consistent measurement of PPG readingsassociated with the driver, wherein at least one PPG waveform signal isdiscarded that is determined to be inconsistent with the plurality ofPPG waveform signals.
 20. The computer readable storage medium of claim17, wherein processing the refined PPG signal includes filtering the PPGmeasurement signal, wherein filtering the PPG measurement signalincludes determining a segment of the PPG measurement signal thatincludes data that is attributed to the motion artifacts measurementsignal, filtering the segment of the PPG measurement signal that isattributed to the motion artifacts as representing the motion artifactsmeasurement signal, and outputting the refined PPG signal, wherein therefined PPG signal is indicative of a measurement of the driver's bloodvolume and blood composition that is decontaminated from the one or moremotion artifacts associated with the driver of the vehicle and thevehicle.